1. Field of the Invention
The present invention relates to a support structure for a light source and a backlight unit for a display device having the support structure, and specifically relates to a support structure for a light source preferably used in a liquid crystal display device including a translucent liquid crystal display panel and a backlight unit for a display device having the support structure.
2. Description of the Related Art
A liquid crystal display device including a translucent liquid crystal display panel or the like, which is cited as an example of a flat-screen display device, generally has a configuration in which a backlight unit is placed at the back of the liquid crystal display panel. The backlight unit is a device having an internal light source, which controls the properties of light emitted from the light source and projects the light toward the back surface of the liquid crystal display panel. The projected light passes through the liquid crystal display panel, making an image displayed visible on the front surface of the liquid crystal display panel.
FIG. 6 is an exploded perspective view schematically illustrating a structure of a backlight unit having a conventional configuration. As shown in FIG. 6, the conventional backlight unit 101 includes a backlight unit 102 that defines a chassis of the backlight unit 101. The backlight unit 102 is a member generally prepared by subjecting a metal plate material to press working, which is formed to be substantially in the shape of a square and of which the opposed longer edges are bent at a predetermined angle toward the front of the backlight unit 101 (the front surface of the backlight unit 101 faces toward the top of FIG. 6, and the same goes for the following descriptions). At the front of the backlight unit 102, a plurality of cold cathode tubes 103 as light sources are installed, and a reflection sheet 104 which reflects the light emitted from the cold cathode tubes 103 is laid.
Rubber holders 133 are respectively attached to the ends of the cold cathode tubes 103. The rubber holders 133 are unitary molded members made of a rubber or other materials that are easy to deform, and have heat resistance and electric insulation. The rubber holders 133 engage with notches 1021 formed on the shorter edges of the backlight unit 102, securing the cold cathode tubes 103 to the backlight unit 102.
With the cold cathode tubes 103 being secured to the backlight unit 102, side holders 108 are attached to the shorter edges of the backlight unit 102. Thus, the ends of the cold cathode tubes 103 are covered by the side holders 108. The side holders 108 are unitary molded members substantially in the shape of a bar, which are made of a resin and the like. Substantially U-shaped notches 1081 are formed on the edges of the side holders 108, so that when the side holders 108 are attached to the backlight unit 102, the cold cathode tubes 103 are placed inside the notches 1081. Accordingly, interference between the side holders 108 and the cold cathode tubes 103 is precluded.
With the side holders 108 being attached, a diffusion plate, a lens sheet, a polarizing reflection film and the like which are members in the shape of a plate or sheet for controlling the properties of the light emitted from the cold cathode tubes 103 are stacked at the front of the side holders 108 and the backlight unit 102. Incidentally, the members in the shape of a plate or sheet are simply referred to as “optical sheets” hereinafter. Then, a frame 106 substantially in the shape of a square with an opening is attached to the front of the optical sheets 105 to be secured to the backlight unit 102. As a result, the optical sheets 105 are secured to the backlight unit 102.
Further, a display panel such as a liquid crystal display panel is placed at the front of the frame 106, and a bezel in the shape of a frame is further attached thereto from the front, whereby a display device is constructed, though they are not illustrated. In some cases, an inverter circuit board which drives the cold cathode tubes 103 as the light sources, other necessary elements such as a circuit board are placed, though they are not illustrated either.
When using a liquid crystal television receiver or the like, which is cited as a specific example of a product incorporating the backlight unit in the case of including a loudspeaker system such as a speaker, there is a case where vibrations generated by the loudspeaker system propagate to the backlight unit to vibrate the backlight unit. If the backlight unit vibrates at a specific vibration frequency, there is a case where resonance occurs to increase amplitude of the cold cathode tubes 103, and the cold cathode tubes 103 come into contact with inner surfaces of the notches 1081 of the side holders 108 to make a contact noise. Therefore, there is a problem that the contact noise could be perceived as an unusual noise by a user, so that quality of the product could be impaired.